EP3713019A1

EP3713019A1 - Insulation displacement connector for sheathed insulated cables

Info

Publication number: EP3713019A1
Application number: EP20163657.8A
Authority: EP
Inventors: Daniela GRAZIANO; Alessandro LAMACCHIA; Riccardo Francesco ROBONE
Original assignee: TE Connectivity Italia SRL; TE Connectivity Italia Distribution SRL
Current assignee: TE Connectivity Italia SRL; TE Connectivity Italia Distribution SRL
Priority date: 2019-03-19
Filing date: 2020-03-17
Publication date: 2020-09-23
Also published as: US11848512B2; IT201900003963A1; US20200303861A1; CN111725646A

Abstract

The present invention relates to an insulation displacement connector (10) for sheathed insulated cables which is configured so as to connect at least one cable to said connector (10), said connector (10) comprising a terminal configured so as to enable electrical connection between a cable and said connector (10) and a housing (11, 12) configured so as to house said terminal inside it and to isolate said terminal with respect to the exterior. In this connector (10), said housing (11, 12) comprises a first portion (11) and a second portion (12) configured so as to mechanically engage with said first portion (11), wherein said first portion (11) is made of a different material from said second portion (12).

Description

TECHNICAL FIELD

The present invention relates to the field of insulation displacement connection systems for sheathed insulated cables. In particular, the present invention relates to an insulation displacement connector for sheathed insulated cables.

PRIOR ART

A new solderless connection technology - IDC (Insulation Displacement Connection) - has been developed in recent decades.
This technology has been extensively developed in the household appliances sector as well as in electronic appliances and more generally in the area of electrical signal transmission. Connections of this type are mostly used for electrical connections not exceeding 25 A and effectively allow a reduction in production costs and easier connection during the production process.
In this application there is no need for preliminary operations on the wires or cables that have to be processed, such as stripping the insulation from the cable, thus making it possible to effectively increase production speed and reduce production costs.
Thanks to this technology, over the years different types of connection systems that allow wires or cables to be electrically connected to a connector, which normally includes an electrical terminal and a housing that houses this electrical terminal, have been developed.
These connectors are commonly known, even in Italian, as RAST connectors (from the German "Raster Anschluss Steck Technik"). This connector is based on a standard (RAST standard) that indicates a type of connection based on multiple connectors characterized by a certain "pitch". Usually the abbreviation is followed by a number representing the particular spacing between the different interconnecting lines. For example, a RAST 5 interconnection comprises a connector with 5 mm pitch contacts.
The RAST standard touches on a number of connector features, including external dimensions, color coding on the housing, polarization mechanisms to prevent mis-assembly, and locking mechanisms to increase interconnection stability.
These connectors must be able to pass specific tests that simulate extreme conditions which these connectors may encounter. Over time, these tests have become more and more selective in order to obtain connectors that are increasingly safe and able to meet the latest standards.
For example, as described in the UL 749 standard, new household dishwashers are required to have components of a defined flammability class or must pass the "Nichrome Wire Test" by 2020. During this test the connector is used as a trigger point, energizing a nickel-chromium coil inserted in place of one of its contacts, energized at 11 A for 20 minutes. Most connectors on the market today create flame in the surrounding areas when subjected to such a test. For this reason, in many situations it is essential to make the connector fireproof in order to pass the test in an appliance.
The object of the present invention is therefore specifically to provide a connection system that has high flammability resistance and is therefore able to pass the various tests required to meet current safety parameters.

SUMMARY

The present invention is based on the idea of providing a connection system comprising a first and a second portion mechanically connected to each other and made of different materials.
According to one embodiment of the present invention, an insulation displacement connector for sheathed insulated cables which is configured so as to connect at least one cable to this connector, is provided. The connector comprises: a terminal configured so as to enable electrical connection between a cable and said connector, and a housing configured so as to house said terminal inside it and to isolate said terminal with respect to the exterior. In the connector, the housing comprises a first portion and a second portion configured so as to mechanically engage with the first portion, wherein the first portion is made of a different material from the second portion. This embodiment is particularly advantageous as it makes it possible to provide a connector having different characteristics in different parts of the connector. For example, the different parts may have different heat resistance. In fact, if there is a need to have a connector that is able to reach a high temperature in a certain part for a long period of time, it will be possible to construct the connector by mechanically coupling together a plurality of parts having different characteristics. In this way, instead of making the entire connector from extremely expensive and high-temperature-resistant material, it will be possible to limit this to the only portion where high thermal stress is expected, thus reducing the cost of the connector. Thanks to mechanical engagement between the first portion and the second portion, it will therefore be possible to mechanically connect the two portions with extreme ease, providing a connector which is geometrically identical to one having a uniform body (as known in the prior art), but which has different properties.
According to a further embodiment of the present invention, a connector is provided in which the first portion is made of a material which offers higher resistance to flammability than the resistance to flammability of the second portion. This solution is particularly advantageous as it offers a connector comprising two parts having different flammability resistance. The portion where higher thermal stress is expected will have a material with higher flammability resistance than the rest of the connector.
According to a further embodiment of the present invention, a connector is provided in which the first portion comprises at least one of the following compositions: polyamide with 30% glass fiber, polybutylene terephthalate with 30% glass fiber, polyethylene terephthalate and polyphenyl sulfide, which is by nature a liquid crystal polymer or another type of self-extinguishing polymer. This solution is particularly advantageous as it provides a connector able to withstand very high thermal stress and therefore able to pass the tests to meet the latest standard requirements, thus providing a particularly safe connector.
According to a further embodiment of the present invention, a connector is provided in which the second portion comprises at least one of polyamide, polyolefin or polybutylene terephthalate.
According to a further embodiment of the present invention, a connector is provided in which the first and second portions comprise a coupling system configured so as to allow coupling between the first portion and the second portion. Thanks to this system it will be possible to mechanically connect the first portion to the second portion by a mechanical system commonly known in the prior art.
According to a further embodiment of the present invention, a connector is provided in which the second portion comprises at least one male coupling system including at least one engaging projection configured to engage the first portion with the second portion by means of resilient deformation of the engaging projection. This solution is particularly effective as it enables the first portion to be mechanically coupled to the second portion by means of resilient deformation, thus enabling the two elements to be coupled reversibly. In addition, resilient deformation ensures connection between the two portions.

BRIEF DESCRIPTION OF THE FIGURES

The present invention will be described with reference to the appended figures, in which the same numbers and/or references indicate the same and/or similar and/or corresponding parts of the system.

Figure 1 shows diagrammatically a three-dimensional view of an insulation displacement connection system for sheathed insulated cables according to the prior art.
Figure 2 shows diagrammatically a three-dimensional view of an insulation displacement connection system for sheathed insulated cables according to one embodiment of the present invention.
Figure 3 shows diagrammatically a three-dimensional view of a first portion of the insulation displacement connection system for sheathed insulated cables according to the present invention.
Figure 4 shows diagrammatically a three-dimensional view of a second portion of the insulation displacement connection system for sheathed insulated cables according to the present invention.

DETAILED DESCRIPTION

The present invention is described below with reference to particular embodiments, as described in the attached plates of drawings. However, the present invention is not limited to the particular embodiments described in the detailed description below and illustrated in the figures, but rather the embodiments described simply exemplify the various aspects of the present invention, the purpose of which is defined by the claims. Further changes relating to the present invention will become clear to a person skilled in the art.
Figure 1 shows a RAST-type connector 100 with 5mm pitch known in the prior art. In particular, the connector shown in the figure is commonly known as an "AMP multifitting mark II", the technical characteristics of which can be found in the catalogue "RAST CONNECTOR SYSTEM IDC & CRIMP CONNECTOR SYSTEM AND RAST TAB HEADER" (catalogue number 1-1773727-3, Revised 4-14) from TE Connectivity Ltd. This connector 100 has four interconnecting lines.
However, as will be clear from the rest of this description, although a particular shape of connector (that of the "AMP multifitting mark II") is illustrated in the figures, clearly the same inventive concept presented here can be applied to any other type of connector having different shapes and characteristics from those described in the figure; to, for example, any of the connectors in the above-mentioned catalogue.
As may be seen, this connector comprises a single body and includes an upper portion 101 where the cables are coupled to the connector 100 and a lower portion 102 where the connector 100 is electrically connected to an external element.
Although not shown, it is clear that inside the connector 100 there is a terminal configured to allow electrical connection between the connector 100 and at least one cable to which the connector is connected.
The cable preferably includes a conductive inner section and an insulating cover commonly referred to as a sheath. The internal conductive section may comprise either a single wire or a plurality of twisted wires (strands) allowing even distribution of the current density passing through the cable.
Further technical details of the connector will be omitted here because they are not necessary for the description of the present invention which, as will be clarified later, is not limited to the particular connector shown in the figures ("AMP multifitting mark II connector"), but can be applied to any type of connector.
The present invention is based on the discovery that the thermal stresses to which a connector is subjected are not uniform, and therefore some portions of the connector must withstand higher loads while other portions are subject to lower loads.
Figure 2 shows a connector 10 having an external geometry similar to the connector 100 shown in Figure 1, according to a particular embodiment of the present invention.
As can be seen in the figure, the connector 10 comprises a first upper portion 11 and a second lower portion 12. In this way the connector 10 is formed by mechanical coupling between two different elements represented by the first portion 11 and the second portion 12.
The fact that the connector 10 is formed by two different mechanically coupled portions makes it possible to have a connector 10 formed of two bodies of different material, therefore having different mechanical and chemical properties.
For example, if it has been established that the higher thermal stress occurs in a particular area of the connector 10, one part may be made more resistant to flammability and one part less resistant.
For example, as previously described, in the particular example shown in the figure, the inventor, by carrying out particular tests, ascertained that the upper portion 101 of the connector 100 shown in the figure ignited when subjected to the "Nichrome Wire Test". The inventor therefore conceived of making the first portion 11 of a material offering a higher flammability resistance than that of the second portion 12.
This is achieved by dividing the connector 10 into two portions and inserting particularly flammability-resistant materials into the first portion 11.
By way of example, without being not limited to the particular choice of materials listed here, the first portion 11 may include at least one of the following compositions: polyamide with 30% glass fiber, polybutylene terephthalate with 30% glass fiber, polyethylene terephthalate and polyphenyl sulfide, which is a liquid crystal polymer, or another type of polymer that is by nature self-extinguishing.
The second portion 12 is preferably made of polyamide, polyolefin or polybutylene terephthalate.
The geometrical characteristics of the first and second portions 11 and 12 that enable coupling between these portions will be presented in detail below with reference to Figures 3 and 4.
In particular, Figure 3 shows the first portion 11 which, as mentioned above, is preferably made of a material that offers higher flammability resistance than the flammability resistance of the second portion 12.
As shown in the figure, the first portion 11 has a female coupling system in its lower part that can connect the first portion 11 to the second portion 12 mechanically, as will be described in detail below.
In particular, in the example shown in the figure, this coupling system includes a plurality of contact surfaces 112 against which projections on the second portion 12, which will be described later, can be secured. Although not shown in the figure because they are hidden inside the first portion 11, as will be clearer from the remainder of this description, additional contact surfaces 112 on the first portion 11 are located in different planes in order to provide an effective mechanical fixing between the first portion 11 and the second portion 12.
It is also clear that the coupling system can be made in any other way equivalent to that shown in this description and known to those skilled in the art.
For example, the first portion 11 may include a female coupling system comprising one or more engaging holes that allow one or more end portions of the second portion 12 to be inserted into these holes, so that the first portion 11 can be mechanically fixed to the second portion 12. It is clear that these holes, located for example on the inner or outer side walls of the first portion 11, can be used in combination or alternatively with the contact surfaces 112.
In particular, the term side surfaces refers to all those surfaces perpendicular to the front surface (front view in Figure 3) and extending along the coupling direction between the first portion 11 and the second portion 12.
In addition, as shown in Figure 3, the first portion 11 includes two grooves 199 which are configured to accommodate the external coupling elements 123 shown in Figure 4.
As shown in Figure 3, the second portion 12 includes a male coupling system comprising a plurality of projecting elements 121-122 extending from the main body of the second portion 12 along a direction in which the second portion 12 is mechanically coupled to the first portion 11. These projecting elements 121-122 therefore enable the second portion 12 to be mechanically coupled to the female coupling system of the first portion 11.
In particular, the plurality of projecting elements 121-122 extend perpendicularly from the main body of the second portion 12 and have a catch 121a-122a, represented by a projection, configured so as to contact the contact surfaces 112 of the female coupling system of the first portion 11.
It is therefore clear that the projecting elements 121-122 are able to be deformed in a direction perpendicular to the direction of extension of the projecting elements 121-122 so that the catches 121a-122a can contact the contact surfaces 112 of the first portion 11.
In fact, during the coupling operation, the catches 121a-122a will contact the surface of the first portion 11, causing the projecting elements 121-122 to flex and then return to their perpendicular positions once the catches 121a-122a contact the contact surfaces 112, substantially providing a kind of snap-fastening system. The projecting elements 121-122 are thus able to block relative movement between the first portion 11 and the second portion 12 by means of their terminal portions including the catches 121a-122a.
Therefore, when finally positioned between the first portion 11 and the second portion 12, the projections 121a-122a will be correctly positioned at a predetermined position along the contact surfaces 112.
It is clear that the number of projecting elements 121-122 can be varied as desired, depending on requirements. The projecting elements may also be positioned in different planes in order to ensure better mechanical coupling.
In addition, the second portion 12 includes the second projecting elements 124 and 125.
Although the present invention has been described with reference to the embodiments described above, it will be clear to those skilled in the art that it is possible to make various modifications, variations and improvements to the present invention in the light of the teaching described above and within the scope of the appended claims without departing from the subject-matter and scope of protection of the invention.
For example, although it has been shown that the first portion 11 has a female coupling system and the second portion 12 has a male coupling system, it is possible to make the coupling system in the opposite way, i.e. with the first portion 11 having a male coupling system and the second portion 12 having a female coupling system.
For example, although a particular mechanical connection between the first portion 11 and the second portion 12 has been described, it is clear that this mechanical connection is not limited to the particular embodiment described in the figure, but can be any mechanical connection known to those skilled in the art.
Finally, it is clear that the example shown in the figures describes a multiple connector configured to allow coupling to four cables (thus having four interconnecting lines), but it is possible to apply the invention to larger or smaller connectors having more or fewer interconnecting lines. Similarly, if the connector is larger or smaller than those shown in the figures, it may have a number of projections on the second portion which is greater or smaller than that described in the figures.
In addition it is clear that, although it has been shown that the connector 10 is made by mechanical coupling between two elements (the first and second portions 11, 12), this connector can also comprise more than two elements having different flammability-resistance characteristics.
Finally, those areas considered to be known to those skilled in the art have not been described in order to avoid unnecessarily obscuring the invention described.
Consequently, the invention is not limited to the embodiments described above but is only limited by the scope of protection of the attached claims.

LIST OF REFERENCE NUMBERS

100:: connector
101:: upper portion
102:: lower portion
10:: connector
11:: first portion
12:: second portion
112:: contact surfaces
121-122:: projecting elements
121a-122a:: catches
124, 125:: second projecting elements

Claims

An insulation displacement connector (10) for sheathed insulated cables which is configured so as to connect at least one cable to said connector (10), said connector (10) comprising:
a terminal configured so as to enable electrical connection between a cable and said connector (10);

a housing (11, 12) configured so as to house said terminal inside it and to isolate said terminal with respect to the exterior

said connector (10) being characterized in that:
said housing (11, 12) comprises a first portion (11) and a second portion (12) configured so as to mechanically engage with said first portion (11), wherein said first portion (11) is made of a different material from said second portion (12).
The connector (10) according to claim 1, wherein said first portion (11) is made of a material which offers higher resistance to flammability than the resistance to flammability of said second portion (12).
The connector (10) according to any one of claims 1 or 2, wherein said first portion (11) comprises at least one of the following compositions: polyamide with 30% glass fiber, polybutylene terephthalate with 30% glass fiber, polyethylene terephthalate and polyphenyl sulfide.
The connector (10) according to any one of claims 1 to 3, wherein said second portion (12) comprises at least one of polyamide, polyolefin or polybutylene terephthalate.
The connector (10) according to any one of claims 1 to 4, wherein said first and said second portions (11, 12) comprise a coupling system (112, 121-122, 121a-122a) configured so as to allow coupling between said first portion (11) and said second portion (12).
The connector according to any one of claims 1 to 5, wherein said second portion (12) comprises a male coupling system comprising at least one engaging projection (121-122, 121a-122a) configured to engage said first portion (11) with said second portion (12) by means of resilient deformation of said engaging projection (121-122, 121a-122a).